Joe Gallen believes James Bolton has the quality to help Pompey challenge for League One promotion next season.
The right-back joins on a free transfer from Shrewsbury and has penned a three-year deal.
Bolton represents Pompey’s first signing of the summer and will offically become a Fratton Park player on July 1.
The 24-year-old’s arrival looks to signal the end of Nathan Thompson’s Blues career.
Bolton has been on Kenny Jackett’s radar for some time.
And Gallen is confident the former Gateshead defender can impact Pompey’s Championship charge.
The assistant manager said: ‘He’s someone we’ve been tracking and has always played well against us over the past couple of seasons.
‘James is solid, a dependable full-back and a positive character – he’s going to be a good addition to our squad.
‘You need to defend, but also be able to provide service to the attacking players and we believe he can do both.
‘He was part of a Shrewsbury side that narrowly missed out on promotion, so he’s played at the top end of this division, which is where we expect to be next season.
‘We think we can improve him and that he can progress at this club, but he already brings a lot to the table.’
Bolton represents Pompey’s third signing from Shrewsbury in as many transfer windows.
Goalkeeper Craig MacGillivray joined the Blues last summer, with Bryn Morris arriving in January.